Housing starts in the United States surged 15 percent in September to the highest level in four years, adding to signs the industry at the heart of the financial crisis is on the road to recovery.

Starts jumped to an 872,000 annual rate last month, the most since July 2008 and exceeding all forecasts in a Bloomberg survey of economists, Commerce Department figures showed Wednesday. The median estimate of 81 economists surveyed by Bloomberg called for 770,000. An increase in building permits may mean the gains will be sustained.

A pickup in sales stoked by record-low mortgage rates and population growth combined with dwindling supply indicates construction can continue strengthening, contributing more to economic growth. At the same time, the level of starts remains below the pre-recession peak, limiting how much the industry can boost the rate of expansion.

"The housing market certainly has turned," said Brian Jones, a senior U.S. economist at Societe Generale, whose forecast for 790,000 starts was among the highest. "But we still have a long way to go. The good thing is that construction will pull employment with it."

Estimates in the Bloomberg survey for housing starts ranged from 735,000 to 800,000, and the prior month was revised up to 758,000 from a previously reported 750,000 pace.

Over the past 12 months, work began on 34.8 percent more homes, the biggest year-over-year gain since April.

The brighter building environment has made construction companies less pessimistic. The National Association of Home Builders/Wells Fargo builder sentiment index increased to 41 this month, the highest since June 2006 and the sixth-straight gain. Still, readings below 50 mean more respondents said conditions were poor.

Building permits, a proxy for future construction, jumped to an 894,000 annual rate, also exceeding the median forecast and the most since July 2008. They were projected to rise to 810,000, with a range of 780,000 to 850,000.

The number of permits swelled by 45.1 percent since September 2011, the biggest annual jump since 1983.

Construction of single-family houses climbed 11 percent from August to a 603,000 rate. Work on multifamily homes, such as apartment buildings, increased 25.1 percent to an annual rate of 269,000.

A harbinger of progress for home builders, demand for new homes has hovered at a two-year high. Homes sold at a 373,000 annual pace in August and at a 374,000 rate in July, the best two months since the March-April 2010, according to Commerce Department figures.